High internal phase Pickering emulsions stabilized by a cod protein-chitosan nanocomplex for astaxanthin delivery.

High internal phase Pickering emulsions (HIPPEs) stabilized by a food protein have attracted widespread attention. In this study, a novel cod protein-chitosan nanocomplex was prepared through electrostatic interactions and used as a particle emulsifier to stabilize the oil-water interface. The application of the cod protein-chitosan nanocomplex was demonstrated in the formation of stable HIPPEs with an internal phase as high as 84%. The influence of the system composition on the stability, microstructure and rheology of the HIPPEs was determined. The HIPPEs stabilized by the cod protein-chitosan nanocomplex formed a compact three-dimensional network structure, which gave the emulsion a higher storage modulus, viscoelasticity and good thixotropy. Interestingly, the chemical stability of astaxanthin was significantly improved by the developed HIPPEs. The bioavailability of astaxanthin in the HIPPEs stabilized by the nanocomplexes of 2.0% (w/w) cod protein and 0.1% (w/w) chitosan reached 49%. In summary, these results demonstrated that the food-grade cod protein-chitosan nanocomplex had potential in the development of HIPPEs, which could be used as carriers for hydrophobic bioactive compound delivery.